Is an oath not to wear clothing or ride a mount one is currently wearing or riding broken immediately?
General Chapter
Al-Mughni
Book of Expiations
Primary text
If a person swears not to wear a garment he is currently wearing, the oath is broken immediately if he removes it; otherwise, it is broken if he continues wearing it. Similarly, if he swears not to ride a mount he is currently riding, he must dismount immediately, or the oath is broken by continuation. This is the view of Al-Shafi'i and the Ashab al-Ra'y. The rationale is that continuing to wear or ride is still termed 'wearing' or 'riding,' and the person is described as a wearer or rider, as evidenced by saying 'I wore this cloth for a month.' The religious law (Shar') considers continuation the same as initiation in this context, as seen in Ihram where continuing the wearing of tailored garments requires expiation just like initiating it.
Supporting text
Abu Thawr argues that the oath is not broken by merely continuing the wearing or riding until a new act is initiated, drawing an analogy to an oath not to marry or purify oneself, where continuation alone does not break the oath. This is differentiated from marriage, as one does not say 'I married for a month' but 'Since a month ago,' which is why continuation in Ihram is not treated the same as initiation regarding prohibition.